LOS ANGELES — Building on California’s ambitious effort to curb greenhouse gas emissions, Gov. Jerry Brown on Wednesday called on the state to further slash its carbon footprint over the next 15 years.

Brown set a new target of reducing emissions to 40 percent below 1990 levels by 2030, calling it the most aggressive benchmark enacted by a government in North America.

The goal is a mile marker on the way to cutting emissions by 80 percent from 1990 levels by 2050 that was set by Brown’s predecessor, former Gov. Arnold Schwarzenegger.

LOS ANGELES — Volunteers who patrol California beaches for plastic, cigarette butts and other litter will be on the lookout this winter for flotsam from last year’s monstrous tsunami off Japan’s coast.

Armed with index-size cards, beachcombers will log water bottles, buoys, fishing gear and other possessions that might have sailed across the Pacific to the 1,100-mile shoreline.

LOS ANGELES — Ancient humans fashioned hand axes, cleavers and picks much earlier than believed, but didn’t take the stone tools along when they left Africa, new research suggests.

A team from the United States and France made the findings after traveling to an archaeological site along the northwest shoreline of Kenya’s Lake Turkana. Two-faced blades and other large cutting tools had been previously excavated there along with primitive stone flakes.